A/C muffler

[Wayne M.]

Re: A/C muffler

.....the elusive 68 only, 3923139. I still think for reliability the more service worthy square types made their way back in time to replace the less reliable and older binocular mufflers needing replacement, ....

Dale -- and checking Chev parts books over the C2 early C3 era bears this out.

[Dale C.]

Re: A/C muffler

This is like a tennis match or I’ll see yours and raise you 50. I found this in the 1968 Chevy service Manual. Why so much printer evidence for that 3923139 muffler if the actual production one was the boxed one? Would the judges zing me if I had that binocular one on my 68, cause, I’m putting it there????????????? Wayne could you ref. the parts book that shows the square muffler for 68? I have the 53 to 72 parts book and it does show the binocular type p 9-15p but its different, as the hose are the crimped which is a sig. ch. that happened in 69. On p. 9-7 you again see the 3923139 listed for 68 only.
Dale

[Joe L.]

Re: A/C muffler

Dale

Dale-----


As far as PRODUCTION utilization goes, the GM #3923139 was uniquely applicable to 1968. It did later become the SERVICE piece for all 1967 applications with C-60, though.

[Wayne M.]

Re: A/C muffler


Dale -- going back to your post #1 of this thread, in your two pics of the binocular "139", is that a GM sticker on there, or is the part # just written on in ink ?

The reason I ask is that I've seen another (off my eBay pic collection) that looks like yours (1st pic, left), and the seller is claiming NOS 1968 (but no part # sticker). I also show a few more eBay 1968 "139's" with square manifold types to fill my thumbnail quota ; two of them with GM tags.

[Terry M.]

Re: A/C muffler

Wayne the third picture looks like the muffler pipe to block joint has been repaired. No criticism, just an observation.

[Dick W.]

Re: A/C muffler

I think that the "binocular" style would be judged as a service replacement until there is good documentation otherwise. The picture in the service manual and the AIM does not constiture good documentation

[Wayne M.]

Re: A/C muffler

Wayne the third picture looks like the muffler pipe to block joint has been repaired. ....

Terry -- agree; the seller's eBay name is HarleyJim, claimed NOS, got $100. for it .

[Dale C.]

Re: A/C muffler

Wayne
Wayne

Dale

[Dale C.]

Re: A/C muffler

That was worthless, as the text in the service manual, general description section, states "the corvette is a four season system", No way is our car plumed like that upper portion of the diagram 1A-21 fig. 28. I guess it all depended on which bin of the day the muffler was drawn from for production.
Dale

[Dale C.]

Re: A/C muffler

Dick

Dale

[Terry M.]

Re: A/C muffler

Dick

Dale

Dale,
If you have spent twenty or forty years using Chevrolet Service Manuals you would have seen, like many of us senior folks have, drawings that continue in the Service Manual or AIM for years and years that are not accurate. Try following the C3 Corvette electrical wiring diagram in either the AIM or the CSM (Chevrolet Service Manual). Neither is accurate, and the inaccuracies continue in those books year after year. In fact one vendor has made a good business of selling wiring diagrams that he modified to improve their accuracy.

My post on December 13 further attempted to explain why the AIMs did not need to contain accurate configuration information, but I thought in the interest of the holiday season I would take another run at this.

[Dale C.]

Re: A/C muffler

Terry

Merry Christmas
Dale

[Terry M.]

Re: A/C muffler

If you firmly believe the binocular stile is the correct configuration for your 1968 -- stand up for your beliefs. Worst case, the point loss will be minimal.

From the sound of all these posts it does appear there may be some room for doubt -- and you can always bring the drawings you have with you. Friendly, brief conversation is always interesting, and everyone learns from it.

[Jack H.]

Re: A/C muffler

A couple of things to consider...

First, the AIM drawings were intended for limited use consumption (in-house communication between designers and production). You can't assume they're 100% correct in all aspects especially physical format.

Was it worth it to sit down a draftsman and re-draw this/that simply because a part that had changed physical appearance but installed in identical fashion changed? Naw!

GM/Chevy would simply re-use 'file footage' and update the PN... So, you need to physically pull the drawing of the part indicated by the AIM and you can't even trust that to be 100% accurate. Why?

Well, sometimes there were multiple suppliers qualified under that drawing and their parts deviated from the physical drawing in subtle ways. Also, you don't know what qty of on-hand inventory there was at the final assy plant of the part the 'new' widget replaced. They might have continued to use the earlier style part and there are cases where that qty was SO extensive that the new replacement part never actually made it into production!

It's not a matter of dis-believing what's published in black and white... It's a matter of really understanding what the drawing(s) represent and cutting some 'slack' in the interpretation. That's one of the reasons senior judges REALLY prefer to see a healthy cross-section of 'untouched' original cars from the era before they accept difference(s) from existing norms.

[Terry M.]

Re: A/C muffler

GM/Chevy would simply re-use 'file footage' and update the PN... So, you need to physically pull the drawing of the part indicated by the AIM and you can't even trust that to be 100% accurate. Why?

Well, sometimes there were multiple suppliers qualified under that drawing and their parts deviated from the physical drawing in subtle ways. Also, you don't know what qty of on-hand inventory there was at the final assy plant of the part the 'new' widget replaced. They might have continued to use the earlier style part and there are cases where that qty was SO extensive that the new replacement part never actually made it into production!

Jack, One of the more interesting examples of this is the much talked about configuration of the inner-upper control arm shaft configuration. Some shafts are rounded where the mounting studs pass through (where the alignment shims go) and some are more square shaped. I once had the chance to examine the print of this piece in the home of a former Saginaw employee. During a tech session he pointed us to a note on the print showing an alternate design. The different shapes indicated different suppliers according to that note.

During his lifetime he was reluctant to share those drawings. Sadly when that person passed away his stash of prints were lost to us, as far as I have been told.